There are a wide variety of gate or sliding plate valves known in the art. Typical examples of such prior art valves are set forth below.
U.S. Pat. No. 564,378 discloses a gate valve which has a renewable seat so that when the seat becomes worn and the valve leaks, the seat may be readily replaced to provide appropriate sealing.
U.S. Pat. No. 2,048,696 discloses a valve having a retractable damper which is water cooled to prevent warpage and which is positioned in relation to an air inlet so that air pressure, stack suction and damper weight help to keep the damper against the seat of the valve.
U.S. Pat. No. 2,580,595 discloses a sliding plate valve in which the plate is oriented horizontally and in which a tubular sleeve is employed to clamp the plate against the valve seat.
U.S. Pat. No. 2,946,349 discloses a plate valve in which the plate is vertically operated and which has a specially designed, shiftable clamp member to facilitate operating the plate valve.
U.S. Pat. No. 4,506,865 discloses a valve housing for a gate valve which has ribs provided along the lower portion of the wall of the housing. These ribs apparently operate to collect particulate matter from the fluids passing through the valve, thereby forming a layer of solids which protects the valve housing from abrasion.
Notwithstanding the foregoing, there still remains a need for shut-off valves that can be used in piping systems carrying high temperature gases. Indeed, there is a particular need for shut-off valves that can be used in horizontal piping runs bearing high temperature gases.